EP3624574A1 - System for cooling an electronic image assembly - Google Patents

Abstract

A system for cooling an electronic image assembly with ambient gas, the system comprising:a plurality of channels placed behind the electronic image assembly, each channel having an inlet and exit;a first manifold in gaseous communication with the inlet of each channel;a second manifold in gaseous communication with the exit of each channel;a fan positioned to force ambient gas through the channels;a front plate placed in front of the electronic image assembly, the space between the front plate and the electronic image assembly defining a front channel;a circulating fan positioned to force circulating gas through the front channel; anda cross through plate having a first pathway for circulating gas traveling through the front channel and a second pathway for ambient gas traveling through the plurality of channels behind the electronic image assembly.

Description

Technical Field
• Exemplary embodiments generally relate to cooling systems and in particular to cooling systems for electronic displays.
Background of the Art
• Improvements to electronic displays now allow them to be used in outdoor environments for informational, advertising, or entertainment purposes. While displays of the past were primarily designed for operation near room temperature, it is now desirable to have displays which are capable of withstanding large surrounding environmental temperature variations. For example, some displays are capable of operating at temperatures as low as -22F and as high as 113 F or higher. When surrounding temperatures rise, the cooling of the internal display components can become even more difficult.
• Additionally, modern displays have become extremely bright, with some backlights producing 1,000-2,000 nits or more. Sometimes, these illumination levels are necessary because the display is being used outdoors, or in other relatively bright areas where the display illumination must compete with other ambient light. In order to produce this level of brightness, illumination devices and electronic displays may produce a relatively large amount of heat.
• Still further, in some situations radiative heat transfer from the sun through a front display surface can also become a source of heat. In some locations 800-1400 Watts/m² or more through such a front display surface is common. Furthermore, the market is demanding larger screen sizes for displays. With increased electronic display screen size and corresponding front display surfaces, more heat will be generated and more heat will be transmitted into the displays.
• Exemplary modern displays have found some effective means for cooling the displays including circulating a closed loop of gas around the display and drawing ambient gas through the display so that the closed loop of gas may be cooled (as well as portions of the electronic display). Various thermal communications have been discovered which can transfer heat away from the sensitive electronic components and out of the display. Heat exchangers were found to produce an excellent means for transferring heat between the closed loop of gas and the ambient gas. However, previous designs for moving the gas through the display have been found to generate an undesirable amount of noise emission from the display as well as thermal gradients where portions of the display were cooled but others remained warm.
• When using LCD displays, it was found that backlights were often a source of heat and it was desirable to move gas across the rear surface of the backlight in order to cool it. While desirable, it was thought that the front surface of the backlight could not be cooled for fear that the backlight cavity would become contaminated with dust, dirt, or other particulate.
Summary of the Exemplary Embodiments
• Exemplary embodiments use a combination of circulating gas and ambient gas in order to adequately cool an electronic display. Circulating gas may be used to remove heat from the front of the image assembly. When using a LCD as the electronic image assembly, circulating gas may also be used to remove heat from the backlight cavity of the LCD. Because the gas is only circulating within the display, it can remain free of particulate and contaminates and will not harm the display.
• Ambient gas may be ingested into the display in order to cool the circulating gas. The ambient gas and the circulating gas may be drawn through a heat exchanger which will allow the heat to transfer from the circulating gas to the ambient gas, preferably without letting the ambient and circulating gases mix with one another. An exemplary embodiment would use a cross-flow heat exchanger. An additional flow of ambient gas can be drawn across the rear surface of the image assembly to remove heat from the rear portion of the image assembly. When using a LCD as the electronic image assembly, this additional flow of ambient gas can be used to remove heat from the rear portion of the backlight for the LCD.
• In order to reduce noise emissions, the fans which drive the ambient and/or circulating gas through the heat exchanger may be placed within the heat exchanger, which can then act as a muffler and reduce the noise emitted by the fans. Further, if using the additional ambient gas pathway behind the image assembly, a manifold may be used to collect the ambient gas along an edge of the display and distribute this into a number of smaller flows. The fans for driving this additional ambient gas pathway can be placed within the manifold in order to reduce the noise emitted by the fans and provide an even distribution of ambient gas across the display.
• It has been found that ingesting ambient gas from the top or bottom edge of the display is preferable as these edges are not typically observable to the viewer. However, when ingesting ambient gas from the top or bottom of a portrait-oriented display, it has been found that as the cool ambient gas travels across the rear portion of the electronic image assembly and accepts heat it increases in temperature. Once the cooling air reaches the opposite edge (either top or bottom), it may have increased in temperature substantially and may no longer provide adequate cooling to the opposing portion of the display. Thus, the manifolds herein allow for cool ambient air to adequately cool the entire electronic image assembly in an even manner and reduce any 'hot spots' within the electronic image assembly.
• The foregoing and other features and advantages will be apparent from the following more detailed description of the particular embodiments of the invention, as illustrated in the accompanying drawings.
Brief Description of the Drawings
• A better understanding of an exemplary embodiment will be obtained from a reading of the following detailed description and the accompanying drawings wherein identical reference characters refer to identical parts and in which:
• FIGURE 1A provides a front perspective view of an exemplary embodiment of the electronic display.
• FIGURE 1B provides a rear perspective view of an exemplary embodiment of the electronic display.
• FIGURE 2 provides a rear perspective view similar to that shown inFigure 1B where the rear cover has been removed.
• FIGURE 3 provides a perspective sectional view along the A-A section line shown inFigure 1B.
• FIGURE 4 provides a perspective sectional view along the B-B section line shown inFigure 1B.
• FIGURE 5 provides a perspective sectional view of insert C shown inFigure 4.
• FIGURE 6 provides a perspective sectional view of one embodiment of the cross through plate.
• FIGURE 7 provides an exploded perspective view of one exemplary embodiment of the heat exchanger and fan assembly.
• FIGURE 8 provides a perspective sectional view of another embodiment which uses a flow of circulating gas through the backlight cavity of a liquid crystal display (LCD).
• FIGURE 9 provides a perspective sectional view of an exemplary embodiment which uses a flow of circulating gas through the backlight cavity in addition to the flow of circulating gas between the LCD and front plate.
Detailed Description
• The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity.
• It will be understood that when an element or layer is referred to as being "on" another element or layer, the element or layer can be directly on another element or layer or intervening elements or layers. In contrast, when an element is referred to as being "directly on" another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
• It will be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
• Spatially relative terms, such as "lower", "upper" and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "lower" relative to other elements or features would then be oriented "upper" relative the other elements or features. Thus, the exemplary term "lower" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
• The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/ or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
• Embodiments of the invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing.
• For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention.
• Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
• FIGURE 1A provides a front perspective view of an exemplary embodiment of theelectronic display 100. A transparentfront plate 10 is placed on the front portion of the display to protect the internal components and allow the images produced by thedisplay 100 to be seen. Some embodiments may use glass as the transparentfront plate 10. Exemplary embodiments may use two pieces of glass laminated with index-matching optical adhesive. Somefront plates 10 may provide other utility such as antireflection or polarizing functions. Aninlet aperture 24 andexit aperture 25 may be provided in the housing so that thedisplay 100 can accept ambient gas for cooling thedisplay 100.
• FIGURE 1B provides a rear perspective view of an exemplary embodiment of theelectronic display 100. Arear cover 15 may be used to provide access to the internal components of thedisplay 100.
• FIGURE 2 provides a rear perspective view similar to that shown inFigure1B where therear cover 15 has been removed.Ambient gas 200 may be ingested into the display through theinlet aperture 24 and pass through aheat exchanger 45 and exit the display through theexit aperture 25. Theambient gas 200 may be drawn into the display and forced through theheat exchanger 45 using heatexchanger fan assembly 46. An exemplary placement for the heatexchanger fan assembly 46 is discussed further below, but in many embodiments thefan assembly 46 can be placed near theinlet aperture 24 and/or exitaperture 25 and may or may not be placed within the heat exchanger 45 (as shown inFigure 2).
• Optionally,ambient gas 210 may also be ingested into the display through inlet aperture 24 (or a separate inlet aperture).Ambient gas 210 may then be directed through afirst manifold 30 which travels along the edge of the display. Thefirst manifold 30 accepts the single larger inlet flow ofambient gas 210 and distributes it into a plurality of smaller flows (channels 60) across the display. Asecond manifold 35 may be placed along the opposite edge of the display as thefirst manifold 30. Thesecond manifold 35 accepts the plurality of smaller flows (channels 60) and combines them into a single flow and exhausts it out of the exit aperture 25 (or a separate exit aperture). In this embodiment, amanifold fan assembly 211 is used to draw theambient gas 210 into theinlet aperture 24 and force theambient gas 210 across the display. For this particular embodiment, themanifold fan assembly 211 is placed within thefirst manifold 30 and is used to draw theambient gas 210 into the display as well as distribute the single flow into a plurality of smaller flows (channels 60). This is not required however, as some embodiments may place themanifold fan assembly 211 in thesecond manifold 35, or within both the first andsecond manifolds 30 and 35.
• The first andsecond manifolds 30 and 35 may be placed along any opposing edges of the display. However, it is preferable that the first andsecond manifolds 30 and 35 are placed along the vertical edges of the display with thechannels 60 travelling horizontally. Other embodiments may place the first andsecond manifolds 30 and 35 along the horizontal edges of the display with thechannels 60 travelling vertically.
• While both flows of ambient gas may be used in an exemplary embodiment, there is no requirement that they are both used. Some embodiments may use onlyambient gas 200 orambient gas 210. Also, if using both flows ofambient gas 200 andambient gas 210 there is no requirement that they share the same inlet and exit apertures. Thus, there may be separate inlet and exit apertures for the two flows of ambient gas.
• FIGURE 3 provides a perspective sectional view along the A-A section line shown inFigure 1B. Again,ambient gas 200 may be ingested into the display through theinlet aperture 24 and pass through aheat exchanger 45 and exit the display through theexit aperture 25. Theambient gas 200 may be drawn into the display and forced through theheat exchanger 45 using heatexchanger fan assembly 46. Obviously, theinlet aperture 24 may contain a filter or other coverings so that contaminates, insects, garbage, and/or water/fluids cannot easily be ingested into the display. However, an exemplary embodiment would not be damaged if theambient gas 200 contained contaminates as they would only pass through theheat exchanger 45 which may not be susceptible to damage from particulate or contaminates.Exit aperture 25 may also contain some type of covering to ensure that contaminates and/or insects could not enter the display.
• Anelectronic image assembly 50 may be placed behind thefront plate 10. A plurality ofchannels 60 may be placed behind theelectronic image assembly 50.Ambient gas 210 may be forced through thechannels 60 after travelling through the first manifold 30 (not shown here). The flow ofambient gas 210 behind theelectronic image assembly 50 may be used to remove any buildup of heat from the rear portion of theelectronic image assembly 50. It may be preferable to have a thermally conductive surface/plate on the rear portion of theelectronic image assembly 50 so that heat can easily transfer to this surface/plate and be removed by theambient gas 210.
• Thechannels 60 can take on any number of forms. Although shown in this embodiment with a square cross-section this is not required. Other embodiments may containchannels 60 with I-beam cross-sections, hollow square cross-sections, hollow rectangular cross-section, solid rectangular or solid square cross-sections, 'T' cross-sections, 'Z' cross-sections, a honeycomb cross-section, or any combination or mixture of these. Thechannels 60 are preferably thermally conductive and also preferably in thermal communication with theelectronic image assembly 50. Thus, in a preferred embodiment, heat which accumulates on the rear portion of theelectronic image assembly 50 may be transferred throughout thechannels 60 and removed byambient gas 210. Preferably, thechannels 60 are metallic and even more preferably aluminum. Further, in an exemplary embodiment thechannels 60 are in conductive thermal communication with theelectronic image assembly 50.
• FIGURE 4 provides a perspective sectional view along the B-B section line shown inFigure 1B. In this view, the path of the circulatinggas 250 can also be observed. The space between thefront plate 10 and theelectronic image assembly 50 may define afront channel 251, through which the circulatinggas 250 may travel in order to remove any accumulation of heat on the front surface of theelectronic image assembly 50. The circulatinggas 250 is preferably then directed into theheat exchanger 45 where heat may be transferred from the circulatinggas 250 to theambient gas 200. Upon exiting theheat exchanger 45, the circulatinggas 250 may be re-directed into thefront channel 251. In this way, theheat exchanger 45 and thefront channel 251 are placed in gaseous communication with each other.
• The circulatinggas 250 may also be directed over variouselectronic components 7 so that heat may be transferred from theelectronic components 7 to the circulatinggas 250. Theelectronic components 7 could be any one of the following but not limited to: power modules, heat sinks, capacitors, motors, microprocessors, hard drives, AC/DC converters, transformers, or printed circuit boards.
• Also shown in this sectional view is the path of theambient gas 210 travelling down one of thechannels 60 behind theelectronic image assembly 50. In this embodiment, theambient gas 210 is forced out of thefirst manifold 30, across thechannels 60, and into thesecond manifold 35 bymanifold fan assembly 211. In other words, eachchannel 60 preferably has an inlet which is in gaseous communication with thefirst manifold 30 as well as an exit which is in gaseous communication with thesecond manifold 35. As shown in this Figure, the paths of theambient gas 210 and the circulatinggas 250 may cross, but it is preferable to keep the two gases from mixing (as theambient gas 210 may contain particulate or contaminates while the circulatinggas 250 can remain substantially free of particulate and contaminates). It may be preferable to keep the circulatinggas 250 from having particulate or contaminates because it travels in front of theelectronic image assembly 50. Thus, to keep the image quality from being impaired, it may be desirable to keep the circulatinggas 250 clean and prevent it from mixing with theambient gas 210.
• FIGURE 5 provides a perspective sectional view of insert C shown inFigure 4. As noted above, if practicing an embodiment which usesambient gas 210 as well as the circulatinggas 250, the pathways of the two gases may need to cross over one another and it may be desirable to prohibit them from mixing to prevent contamination of sensitive portions of the display. Here, cross throughplate 500 allows the pathways of the two gases to cross over one another without letting them mix together. The cross throughplate 500 in this embodiment contains a series of voids which pass through the plate. A first series ofvoids 550 passes through the cross throughplate 500 and allowsambient gas 210 to travel from thefirst manifold 30 into thechannels 60 which run behind theelectronic image assembly 50. A second series ofvoids 525 pass through the cross throughplate 500 in a direction substantially perpendicular to that of the first series ofvoids 550. The second series ofvoids 525 allows the circulating gas to exit thefront channel 251, cross over theambient gas 210, and continue towards theheat exchanger 45. In this embodiment, a circulatinggas fan assembly 255 is used to draw the circulatinggas 250 through thefront channel 251 and through theheat exchanger 45. Much like the other fan assemblies shown and described here, the circulatinggas fan assembly 255 could be placed anywhere within the display, including but not limited to the entrance/exit of theheat exchanger 45 or the entrance/exit of thefront channel 251.
• FIGURE 6 provides a perspective sectional view of one embodiment of the cross throughplate 500. In this embodiment, the cross throughplate 500 is comprised of a plurality ofhollow blocks 503 sandwiched between atop plate 501 andbottom plate 502 with sections of theplates 501 and 502 removed to correspond with the hollow sections of theblocks 503. A portion of thetop plate 501 has been removed to show the detail of thehollow blocks 503, first series ofvoids 550, and second series ofvoids 525. The cross throughplate 500 could take on any number of forms and could be constructed in a number of ways. Some other embodiments may use a solid plate where the first and second series ofvoids 550 and 525 are cut out of the solid plate. Other embodiments could use two sets of hollow blocks where the hollow sections are perpendicular to each other and the blocks are fastened together. Still other embodiments could use a design similar to those that are taught below for theheat exchanger 45, for example any type of cross-flow heat exchanger design could be used. Thus, an exemplary cross throughplate 500 contains two gaseous pathways where the two pathways do not allow the gaseous matter to mix. Here, the first gas pathway would be 525 while the second gas pathway would be 550.
• FIGURE 7 provides an exploded perspective view of one exemplary embodiment of theheat exchanger 45 andfan assembly 46. In this view, thefan assembly 46 is shown removed from its mounted position within thefan housing 51. In this embodiment, theheat exchanger 45 is divided into twoportions 47 and 48 where thefan housing 51 is used to provide a gaseous communication between the twoportions 47 and 48. Here, thefan assembly 46 is placed between the twoportions 47 and 48. While thefan assembly 46 can be placed anywhere so that it drawsambient gas 200 through theheat exchanger 45, it has been found that placing thefan assembly 46 between the two portions of the heat exchanger can provide a number of benefits. First, the volumetric flow rate of theambient gas 200 through the heat exchanger is high, which results in better cooling capabilities for theheat exchanger 45. Second, the noise produced by thefan assembly 46 can be reduced because the surroundingportions 47 and 48 of theheat exchanger 45 essentially act as a muffler for thefan assembly 46.
• In this embodiment,portion 48 is thinner and longer thanportion 47. This was done in order to free up more space within the housing so that additional electronic components could fit within the housing (adjacent to portion 48). As shown, thefan housing 51 may be used to connect two portions of a heat exchanger which may be of different lengths. As shown,portion 48 of the heat exchanger is thinner than thefan housing 51. In an alternative embodiment, bothportions 48 and 47 may be thinner than thefan assembly 46 such that afan housing 51 may be used to provide a sealed gaseous communication between the two portions, even though they are both thinner than thefan assembly 51. This design may be preferable when it is desirable to create the largest possible heat exchanger 45 (for maximum cooling abilities) even though space is limited. This is of course not required, and other embodiments may have portions which are of equal width and length. Also, although this embodiment uses thefan assembly 46 to drive theambient gas 200, other embodiments could use a fan assembly placed within the heat exchanger to drive the circulatinggas 250 instead and drive theambient gas 200 with another fan assembly (possibly placed within the heat exchanger or located at the entrance/exit of the heat exchanger). Some exemplary embodiments may place fans within theheat exchanger 45 to drive both theambient gas 200 and circulatinggas 250.
• Theambient gas 200 travels through a first pathway (or plurality of pathways) of theheat exchanger 45 while the circulatinggas 250 travels through a second pathway (or plurality of pathways) of theheat exchanger 45. Although not required, it is preferable that the circulatinggas 250 andambient gas 200 do not mix. This may prevent any contaminates and/or particulate that is present within theambient gas 200 from harming the interior of the display. In a preferred embodiment, theheat exchanger 45 would be a cross-flow heat exchanger. However, many types of heat exchangers are known and can be used with any of the embodiments herein. Theheat exchanger 45 may be a cross-flow, parallel flow, or counter-flow heat exchanger. In an exemplary embodiment, theheat exchanger 45 would be comprised of a plurality of stacked layers of thin plates. The plates may have a corrugated, honeycomb, or tubular design, where a plurality of channels/pathways/tubes travel down the plate length-wise. The plates may be stacked such that the directions of the pathways are alternated with each adjacent plate, so that each plate's pathways are substantially perpendicular to the pathways of the adjacent plates. Thus, ambient gas or circulating gas may enter an exemplary heat exchanger only through plates whose channels or pathways travel parallel to the path of the gas. Because the plates are alternated, the circulating gas and ambient gas may travel in plates which are adjacent to one another and heat may be transferred between the two gases without mixing the gases themselves (if the heat exchanger is adequately sealed, which is preferable but not required).
• In an alternative design for a heat exchanger, an open channel may be placed in between a pair of corrugated, honeycomb, or tubular plates. The open channel may travel in a direction which is perpendicular to the pathways of the adjacent plates. This open channel may be created by running two strips of material or tape (esp. very high bond (VHB) tape) between two opposite edges of the plates in a direction that is perpendicular to the direction of the pathways in the adjacent plates. Thus, gas entering the heat exchanger in a first direction may travel through the open channel (parallel to the strips or tape). Gas which is entering in a second direction (substantially perpendicular to the first direction) would travel through the pathways of the adjacent plates).
• Other types of cross-flow heat exchangers could include a plurality of tubes which contain the first gas and travel perpendicular to the path of the second gas. As the second gas flows over the tubes containing the first gas, heat is exchanged between the two gases. Obviously, there are many types of cross-flow heat exchangers and any type would work with the embodiments herein.
• An exemplary heat exchanger may have plates where the sidewalls have a relatively low thermal resistance so that heat can easily be exchanged between the two gases. A number of materials can be used to create the heat exchanger. Preferably, the material used should be corrosion resistant, rot resistant, light weight, and inexpensive. Metals are typically used for heat exchangers because of their high thermal conductivity and would work with these embodiments. However, it has been discovered that plastics and composites can also satisfy the thermal conditions for electronic displays. An exemplary embodiment would utilize polypropylene as the material for constructing the plates for the heat exchanger. It has been found that although polypropylene may seem like a poor thermal conductor, the large amount of surface area relative to a small sidewall thickness, results in an overall thermal resistance that is low. Thus, an exemplary heat exchanger would be made of plastic and would thus produce a display assembly that is thin and lightweight. Specifically, corrugated plastic may be used for each plate layer where they are stacked together in alternating fashion (i.e. each adjacent plate has channels which travel in a direction perpendicular to the surrounding plates).
• FIGURE 8 provides a perspective sectional view of another embodiment which uses a flow of circulatinggas 350 through the backlight cavity of a liquid crystal display (LCD) 300. In this embodiment, aLCD 300 and an associatedbacklight 320 are used as the electronic image assembly. Abacklight wall 330 may enclose the area between theLCD 300 and thebacklight 320 in order to create a backlight cavity. Typically, the backlight cavity is closed to prevent contaminates/particulate from entering the backlight cavity and disrupting the optical/electrical functions of thebacklight 320. However, as discussed above the exemplary embodiments may use a clean gaseous matter for the circulating gases which could now be used to ventilate the backlight cavity in order to cool thebacklight 320 and even the rear portion of theLCD 300. Anopening 340 can be placed in thebacklight wall 330 to allow circulatinggas 350 to flow through the backlight cavity. Afan assembly 360 may be used to draw the circulatinggas 350 through the backlight cavity. In an exemplary embodiment there would be an opening on the opposing backlight wall (on the opposite side of the display as shown in this figure) so that circulatinggas 350 could easily flow through the backlight cavity. In this way, the backlight cavity is placed in gaseous communication with theheat exchanger 45.
• FIGURE 9 provides a perspective sectional view of an exemplary embodiment which uses a flow of circulatinggas 350 through the backlight cavity in addition to the flow of circulatinggas 250 through the front channel 251 (the area defined between theLCD 300 and front plate 10). Circulatingfan assembly 255 may be placed so that it can draw circulatinggas 350 through the backlight cavity as well as circulatinggas 250 through thefront channel 251. As discussed above, the circulatinggases 250 and 350 are preferably forced through the heat exchanger 45 (not shown in this figure) so that they may be cooled by the ambient gas 200 (also not shown in this figure). In this way, both thefront channel 251 and the backlight cavity are placed in gaseous communication with theheat exchanger 45.
• Also shown inFigure 9 is the optional additional flow ofambient gas 210 which may travel immediately behind the electronic image assembly (in this embodiment backlight 320). Once travelling through thefirst manifold 30, theambient gas 210 may pass through thechannels 60 in order to remove heat from thebacklight 320 and even thechannels 60 themselves (if they are thermally conductive). Themanifold fan assembly 211 may be used to draw theambient gas 210 into thefirst manifold 30 and through thechannels 60. Again, the cross thoughplate 500 may be used to allow the circulatinggases 350 and 250 to cross paths with theambient gas 210 without letting the two gases mix.
• In an exemplary embodiment, thebacklight 320 would contain a plurality of LEDs mounted on a thermally conductive substrate (preferably a metal core PCB). On the surface of the thermally conductive substrate which faces thechannels 60 there may be a thermally conductive plate which may be in thermal communication with thechannels 60. In an exemplary embodiment, the thermally conductive plate would be metallic and more preferably aluminum and the thermal communication between thechannels 60 and thebacklight 320 would be conductive thermal communication.
• As noted above, many electronic image assemblies (especially LEDs, LCDs, and OLEDs) may have performance properties which vary depending on temperature. When 'hot spots' are present within an image assembly, these hot spots can result in irregularities in the resulting image which might be visible to the end user. Thus, with the embodiments described herein, the heat which may be generated by the image assembly (sometimes containing a backlight assembly) can be distributed (somewhat evenly) throughout thechannels 60 and thermally-conductive surfaces to remove hot spots and cool the backlight and/or electronic image assembly.
• The circulatinggases 250 and 350,ambient gas 200, and optionalambient gas 210 can be any number of gaseous matters. In some embodiments, air may be used as the gas for all. As well known by those of ordinary skill in the art, air typically contains some amount of water vapor. It should be noted that the use of the term 'gas' herein does not designate pure gas and that it is specifically contemplated that any of the gaseous matters described herein may contain some amount of impurities including but not limited to water vapor. Preferably, because the circulatinggases 250 and 350 may travel in front of the image assembly and backlight respectively, they should be substantially clear, so that they will not affect the appearance of the image to a viewer. The circulatinggases 250 and 350 should also preferably be substantially free of contaminates and/or particulate in order to prevent an adverse effect on the image quality and/or damage to the internal electronic components. It may sometimes be preferable to keepambient gases 200 and 210 from having contaminates as well. Filters may be used to help reduce the particulate withinambient gases 200 and 210. Filters could be placed near theinlet aperture 24 so thatambient gases 200 and/or 210 could be drawn through the filter. However, in an exemplary embodiment the display may be designed so that contaminates could be present within theambient gases 200 and 210 but this will not harm the display. In these embodiments, theheat exchanger 45,manifolds 30 and 35,channels 60, and any other pathway for ambient or circulating gas should be properly sealed so that any contaminates in the ambient gas would not enter sensitive portions of the display. Thus, in these exemplary embodiments, ambient air may be ingested for theambient gases 200 and 210, even if the ambient air contains contaminates or particulate. This can be particularly beneficial when the display is used in outdoor environments or indoor environments where contaminates are present in the ambient air.
• The cooling system may run continuously. However, if desired, temperature sensing devices (not shown) may be incorporated within the electronic display to detect when temperatures have reached a predetermined threshold value. In such a case, the various cooling fans may be selectively engaged when the temperature in the display reaches a predetermined value. Predetermined thresholds may be selected and the system may be configured to advantageously keep the display within an acceptable temperature range. Typical thermostat assemblies can be used to accomplish this task. Thermocouples may be used as the temperature sensing devices.
• It is to be understood that the spirit and scope of the disclosed embodiments provides for the cooling of many types of electronic image assemblies. As used herein, the term 'electronic image assembly' is any electronic assembly for creating an image. At this time this, these are LCD (all types), light emitting diode (LED), organic light emitting diode (OLED), field emitting display (FED), light emitting polymer (LEP), organic electro luminescence (OEL), plasma displays, and any thin/flat panel electronic image assembly. Furthermore, embodiments may be used with displays of other types including those not yet discovered. In particular, it is contemplated that the system may be well suited for use with full color, flat panel OLED displays. Exemplary embodiments may also utilize large (55 inches or more) LED backlit, high definition liquid crystal displays (LCD). While the embodiments described herein are well suited for outdoor environments, they may also be appropriate for indoor applications (e.g., factory/industrial environments, spas, locker rooms) where thermal stability of the display may be a concern.
• As is well known in the art, electronic displays can be oriented in a portrait manner or landscape manner and either can be used with the embodiments herein.
• Having shown and described preferred embodiments, those skilled in the art will realize that many variations and modifications may be made to affect the described embodiments and still be within the scope of the claimed invention. Additionally, many of the elements indicated above may be altered or replaced by different elements which will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.

Claims (15)

1. A system for cooling an electronic image assembly with ambient gas, the system comprising:

   a plurality of channels (60) placed behind the electronic image assembly (50), each channel having an inlet and exit;

   a first manifold (30) in gaseous communication with the inlet of each channel (60);

   a second manifold (35) in gaseous communication with the exit of each channel (60);

   a fan (211) positioned to force ambient gas through the channels (60);

   a front plate (10) placed in front of the electronic image assembly (50), the space between the front plate and the electronic image assembly defining a front channel (251);

   a circulating fan (255) positioned to force circulating gas through the front channel (251); and

   a cross through plate (500) having a first pathway (525) for circulating gas (250) traveling through the front channel (251) and a second pathway (550) for ambient gas (210) traveling through the plurality of channels (60) behind the electronic image assembly (50).
2. The cooling system of claim 1 wherein:
   the channels (60) are in thermal communication with the electronic image assembly (50).
3. The cooling system of claim 1 or 2 wherein:
   the first (30) and second (35) manifolds are placed along a pair of vertical edges of the electronic image assembly (50).
4. The cooling system of any one of claims 1-3 wherein:
   the fan (211) is placed within either the first or second manifold.
5. The cooling system of any one of claims 1-4 wherein:
   the channels (60) are arranged in horizontal rows.
6. The cooling system of any one of claims 1-5 wherein:
   the channels (60) are metallic.
7. The cooling system of any one of claims 1-6 wherein:
   the first (525) and second (550) gas pathways are substantially perpendicular.
8. The cooling system of any one of claims 1-7 wherein:
   the first (525) and second (550) gas pathways do not allow the ambient gas and circulating gas to mix.
9. The cooling system of any one of claims 1-8 further comprising:

   a heat exchanger (45) having first and second gas pathways; and

   a fan assembly (46) placed within the heat exchanger (45) to draw ambient gas (200) through the first gas pathway of the heat exchanger (45);

   wherein the circulating fan (255) is placed to draw circulating gas (250) through the second gas pathway of the heat exchanger (45).
10. The cooling system of any one of claims 1-8 further comprising:

    a heat exchanger (45) in gaseous communication with the front channel (251), the heat exchanger comprising two portions (48) and (47), each portion having first and second gas pathways, where the first gas pathways are in gaseous communication with inlet (24) and exit (25) apertures for ambient gas (200) and the second gas pathways are in gaseous communication with the channel (251); and

    a fan assembly (46) placed between the two portions (48) and (47) of the heat exchanger (45) to force ambient gas (200) through the first gas pathways;

    wherein the circulating fan (255) is positioned to force circulating gas (250) through the second gas pathways.
11. The cooling system of any one of claims 9 and 10 wherein:
    the heat exchanger (45) is comprised of corrugated layers.
12. The cooling system of any one of claims 9 and 10 wherein:
    the heat exchanger (45) is a cross-flow heat exchanger.
13. The cooling system of any one of claims 1-12 wherein:
    the front plate 10 is transparent.
14. The cooling system of any one of claims 1-13 wherein:
    the circulating fan (255) is positioned to force circulating gas in a closed loop that passes through the front channel (251).
15. The cooling system of any one of claims 1-14 wherein:

    the electronic image assembly (50) comprises a backlight; and

    the channels (60) are in thermal communication the backlight.

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